Definition
In an alternating current (AC) circuit, the portion of current or voltage caused by inductance or capacitance rather than by resistance. The reactive component is 90 degrees out of phase with the resistive component and does not perform useful work, but it does contribute to the total current the circuit must carry.
Plain English
The part of an AC circuit's current or voltage that bounces back and forth between the source and components like coils or capacitors. It moves through the wires but doesn't actually do any work — it just stores and releases energy.
Context Anchor
Seen in aircraft electrical theory and maintenance troubleshooting for alternating-current circuits.
Derivation
From Latin reactio, 'a reaction' — react + -ive. In electrical use, it describes the part of the circuit that 'reacts' to changes in current by storing and releasing energy, rather than dissipating it as heat.
Why Pilots Care
Technicians servicing aircraft AC systems need to recognise that reactive current adds to the total load on a generator or wire even though it produces no useful work. Ignoring it can lead to undersized wiring, overheating, or misdiagnosed electrical faults.
Analogy
A spring does not simply stop your push; it stores some of the energy and pushes back. A reactive component in a circuit behaves in a similar way with electrical energy.
Intuition Check
Do not read reactive component as a separate electrical part that is just “quick to respond.” Here it means the stored-and-returned-energy part of a circuit’s opposition to alternating current.
Example Sentence 1
The reactive component of the current in the motor circuit was high because of the large inductive load from the windings.
Example Sentence 2
A failed reactive component in the power supply caused voltage instability during the test.